The present invention relates to an optical disk, an optical disk system and a cryptocommunication method.
In recent years, with the increased use of networks such as the Internet and optical CD ROM disks, network soft key distribution for optical ROM disks has increased. Also, electronic commercial transactions have increased.
Soft key electronic distribution systems for CD-ROM media have been used. In conventional systems, it is known to give passwords and decipher the enciphered soft ciphers recorded on the CD-ROMs in advance. When CD-ROMs are used, however, it is not possible additionally to record on the disks, so that it is not possible to individually set IDs for respective disks. Therefore one password would release the ciphers of all the disks manufactured from the same original disk. For this reason, when CD-ROMs are used, it is necessary to install the disks"" IDs on the hard disks of personal computers, or mail to users IDs prepared centrally.
In electronic distribution systems with conventional optical disks and/or optical disk systems, there is a need to provide the disks and/or systems with IDs and/or cipher keys. It is an object of the present invention to simply provide IDs and cipher keys for ROM disks in electronic distribution systems.
To achieve the objects of the present invention, the pit portions of optical disks are provided with an additional recording area or Burst Cutting Area (hereinafter abbreviated as BCA) overwritten with a bar code and, when the disks are manufactured, IDs differing for each disk and, according to the need, cipher keys for communication and decoding keys for decoding key cipher texts for communication, are recorded individually in the BCA areas. As a result, when the disks have been distributed to users, the user ID numbers, the cipher keys for transmission for communication, and the decoding keys for reception are distributed automatically to the users. It is therefore possible to omit some of the procedures that complicate conventional systems. Also, cryptocommunication and the identification of disks are made possible at the same time.